The present invention relates to a light control device of the type comprising a light control device comprising a plurality of shutter blades, which may also function as an aperture control diaphragm, and means for driving the shutter blades intermittently in response to pulse signals to be transmitted from a control circuit.
In conventional shutter mechanisms of photo cameras, shutter blades are, in general, opened and closed by mechanical forces. For instance, when a film advance lever is operated to advance the film, the power required for actuating the shutter blades is charged and stored in the form of mechanical force. When a shutter release button is depressed, the shutter blades are opened and then closed by the stored driving power. Therefore, unless the shutter driving power is stored in a shutter spring in the form of mechanical force whenever the film advance lever is rotated, the shutter blades cannot be actuated at all. Therefore, the conventional shutter mechanisms of the type described have an inherent undesirable feature in that the shutter blades cannot be actuated many times in succession at a high speed in a relatively short time.
In order to actuate the shutter blades in response to an electrical signal in the conventional shutter mechanism, the shutter release button is mechanically coupled to a solenoid so that when the solenoid is energized in response to the electrical signal, the shutter release button is depressed to open the shutter. However, such arrangement as described above has a disadvantage that the opening of the shutter blades is not in synchronism with the electrical signal because of the time lag required for the solenoid to produce sufficient force to depress the shutter button in response to the electrical signal applied and in view of the time required for transmitting the driving force from the shutter button to the shutter driving means through the mechanical mechanism. Moreover, since the solenoid must be provided and coupled to the shutter release button through a mechanical coupling, the shutter release mechanism driven by the solenoid becomes large in size and complex in construction.
In conventional shutter mechanisms of the type described above, the power required for actuating the shutter blades cannot be applied and stored unless the film advance lever is operated, and the power must be applied and stored each time the shutter blades are opened and closed. Therefore, the continuous motion of an object cannot be photographed on the same film.